Statistics
| Branch: | Tag: | Revision:

root / doc / install.sgml @ a2cfdea2

History | View | Annotate | Download (29.4 kB)

1
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V4.2//EN" [
2
]>
3
  <article class="specification">
4
  <articleinfo>
5
    <title>Ganeti installation tutorial</title>
6
  </articleinfo>
7
  <para>Documents Ganeti version 1.2</para>
8

    
9
  <sect1>
10
    <title>Introduction</title>
11

    
12
    <para>
13
      Ganeti is a cluster virtualization management system based on
14
      Xen. This document explains how to bootstrap a Ganeti node (Xen
15
      <literal>dom0</literal>), create a running cluster and install
16
      virtual instance (Xen <literal>domU</literal>).  You need to
17
      repeat most of the steps in this document for every node you
18
      want to install, but of course we recommend creating some
19
      semi-automatic procedure if you plan to deploy Ganeti on a
20
      medium/large scale.
21
    </para>
22

    
23
    <para>
24
      A basic Ganeti terminology glossary is provided in the
25
      introductory section of the <emphasis>Ganeti administrator's
26
      guide</emphasis>. Please refer to that document if you are
27
      uncertain about the terms we are using.
28
    </para>
29

    
30
    <para>
31
      Ganeti has been developed for Linux and is
32
      distribution-agnostic.  This documentation will use Debian Etch
33
      as an example system but the examples can easily be translated
34
      to any other distribution.  You are expected to be familiar with
35
      your distribution, its package management system, and Xen before
36
      trying to use Ganeti.
37
    </para>
38

    
39
    <para>This document is divided into two main sections:
40

    
41
      <itemizedlist>
42
        <listitem>
43
          <simpara>Installation of the base system and base
44
          components</simpara>
45
        </listitem>
46
        <listitem>
47
          <simpara>Configuration of the environment for
48
          Ganeti</simpara>
49
        </listitem>
50
      </itemizedlist>
51

    
52
    Each of these is divided into sub-sections. While a full Ganeti
53
    system will need all of the steps specified, some are not strictly
54
    required for every environment. Which ones they are, and why, is
55
    specified in the corresponding sections.
56
    </para>
57

    
58
  </sect1>
59

    
60
  <sect1>
61
    <title>Installing the base system and base components</title>
62

    
63
    <sect2>
64
      <title>Hardware requirements</title>
65

    
66
      <para>
67
         Any system supported by your Linux distribution is fine.
68
         64-bit systems are better as they can support more memory.
69
      </para>
70

    
71
      <para>
72
         Any disk drive recognized by Linux
73
         (<literal>IDE</literal>/<literal>SCSI</literal>/<literal>SATA</literal>/etc.)
74
         is supported in Ganeti. Note that no shared storage
75
         (e.g. <literal>SAN</literal>) is needed to get high-availability features. It is
76
         highly recommended to use more than one disk drive to improve
77
         speed. But Ganeti also works with one disk per machine.
78
      </para>
79

    
80
    <sect2>
81
      <title>Installing the base system</title>
82

    
83
      <para>
84
        <emphasis role="strong">Mandatory</emphasis> on all nodes.
85
      </para>
86

    
87
      <para>
88
        It is advised to start with a clean, minimal install of the
89
        operating system. The only requirement you need to be aware of
90
        at this stage is to partition leaving enough space for a big
91
        (<emphasis role="strong">minimum
92
        <constant>20GiB</constant></emphasis>) LVM volume group which
93
        will then host your instance filesystems. The volume group
94
        name Ganeti 1.2 uses (by default) is
95
        <emphasis>xenvg</emphasis>.
96
      </para>
97

    
98
      <para>
99
        While you can use an existing system, please note that the
100
        Ganeti installation is intrusive in terms of changes to the
101
        system configuration, and it's best to use a newly-installed
102
        system without important data on it.
103
      </para>
104

    
105
      <para>
106
        Also, for best results, it's advised that the nodes have as
107
        much as possible the same hardware and software
108
        configuration. This will make administration much easier.
109
      </para>
110

    
111
      <sect3>
112
        <title>Hostname issues</title>
113
        <para>
114
          Note that Ganeti requires the hostnames of the systems
115
          (i.e. what the <computeroutput>hostname</computeroutput>
116
          command outputs to be a fully-qualified name, not a short
117
          name. In other words, you should use
118
          <literal>node1.example.com</literal> as a hostname and not
119
          just <literal>node1</literal>.
120
        </para>
121

    
122
        <formalpara>
123
          <title>Debian</title>
124
          <para>
125
            Note that Debian Etch configures the hostname differently
126
            than you need it for Ganeti. For example, this is what
127
            Etch puts in <filename>/etc/hosts</filename> in certain
128
            situations:
129
<screen>
130
127.0.0.1       localhost
131
127.0.1.1       node1.example.com node1
132
</screen>
133

    
134
          but for Ganeti you need to have:
135
<screen>
136
127.0.0.1       localhost
137
192.168.1.1     node1.example.com node1
138
</screen>
139
            replacing <literal>192.168.1.1</literal> with your node's
140
            address. Also, the file <filename>/etc/hostname</filename>
141
            which configures the hostname of the system should contain
142
            <literal>node1.example.com</literal> and not just
143
            <literal>node1</literal> (you need to run the command
144
            <computeroutput>/etc/init.d/hostname.sh
145
            start</computeroutput> after changing the file).
146
          </para>
147
        </formalpara>
148
      </sect3>
149

    
150
    </sect2>
151

    
152
    <sect2>
153
      <title>Installing Xen</title>
154

    
155
      <para>
156
        <emphasis role="strong">Mandatory</emphasis> on all nodes.
157
      </para>
158

    
159
      <para>
160
        While Ganeti is developed with the ability to modularly run on
161
        different virtualization environments in mind the only one
162
        currently useable on a live system is <ulink
163
        url="http://xen.xensource.com/">Xen</ulink>. Supported
164
        versions are: <simplelist type="inline">
165
        <member><literal>3.0.3</literal></member>
166
        <member><literal>3.0.4</literal></member>
167
        <member><literal>3.1</literal></member> </simplelist>.
168
      </para>
169

    
170
      <para>
171
        Please follow your distribution's recommended way to install
172
        and set up Xen, or install Xen from the upstream source, if
173
        you wish, following their manual.
174
      </para>
175

    
176
      <para>
177
        After installing Xen you need to reboot into your Xen-ified
178
        dom0 system. On some distributions this might involve
179
        configuring GRUB appropriately, whereas others will configure
180
        it automatically when you install Xen from a package.
181
      </para>
182

    
183
      <formalpara><title>Debian</title>
184
      <para>
185
        Under Debian Etch or Sarge+backports you can install the
186
        relevant <literal>xen-linux-system</literal> package, which
187
        will pull in both the hypervisor and the relevant
188
        kernel. Also, if you are installing a 32-bit Etch, you should
189
        install the <computeroutput>libc6-xen</computeroutput> package
190
        (run <computeroutput>apt-get install
191
        libc6-xen</computeroutput>).
192
      </para>
193
      </formalpara>
194

    
195
      <sect3>
196
        <title>Xen settings</title>
197

    
198
        <para>
199
          It's recommended that dom0 is restricted to a low amount of
200
          memory (<constant>512MiB</constant> is reasonable) and that
201
          memory ballooning is disabled in the file
202
          <filename>/etc/xen/xend-config.sxp</filename> by setting the
203
          value <literal>dom0-min-mem</literal> to
204
          <constant>0</constant>, like this:
205
          <computeroutput>(dom0-min-mem 0)</computeroutput>
206
        </para>
207

    
208
        <para>
209
          For optimum performance when running both CPU and I/O
210
          intensive instances, it's also recommended that the dom0 is
211
          restricted to one CPU only, for example by booting with the
212
          kernel parameter <literal>nosmp</literal>.
213
        </para>
214

    
215
        <formalpara>
216
          <title>Debian</title>
217
          <para>
218
            Besides the ballooning change which you need to set in
219
            <filename>/etc/xen/xend-config.sxp</filename>, you need to
220
            set the memory and nosmp parameters in the file
221
            <filename>/boot/grub/menu.lst</filename>. You need to
222
            modify the variable <literal>xenhopt</literal> to add
223
            <userinput>dom0_mem=512M</userinput> like this:
224
<screen>
225
## Xen hypervisor options to use with the default Xen boot option
226
# xenhopt=dom0_mem=512M
227
</screen>
228
            and the <literal>xenkopt</literal> needs to include the
229
            <userinput>nosmp</userinput> option like this:
230
<screen>
231
## Xen Linux kernel options to use with the default Xen boot option
232
# xenkopt=nosmp
233
</screen>
234

    
235
          Any existing parameters can be left in place: it's ok to
236
          have <computeroutput>xenkopt=console=tty0
237
          nosmp</computeroutput>, for example. After modifying the
238
          files, you need to run:
239
<screen>
240
/sbin/update-grub
241
</screen>
242
          </para>
243
        </formalpara>
244

    
245
      </sect3>
246

    
247
      <sect3>
248
        <title>Selecting the instance kernel</title>
249

    
250
        <para>
251
          After you have installed Xen, you need to tell Ganeti
252
          exactly what kernel to use for the instances it will
253
          create. This is done by creating a
254
          <emphasis>symlink</emphasis> from your actual kernel to
255
          <filename>/boot/vmlinuz-2.6-xenU</filename>, and one from
256
          your initrd to
257
          <filename>/boot/initrd-2.6-xenU</filename>. Note that if you
258
          don't use an initrd for the <literal>domU</literal> kernel,
259
          you don't need to create the initrd symlink.
260
        </para>
261

    
262
        <formalpara>
263
          <title>Debian</title>
264
          <para>
265
            After installation of the
266
            <literal>xen-linux-system</literal> package, you need to
267
            run (replace the exact version number with the one you
268
            have):
269
            <screen>
270
cd /boot
271
ln -s vmlinuz-2.6.18-5-xen-686 vmlinuz-2.6-xenU
272
ln -s initrd.img-2.6.18-5-xen-686 initrd-2.6-xenU
273
            </screen>
274
          </para>
275
        </formalpara>
276
      </sect3>
277

    
278
    </sect2>
279

    
280
    <sect2>
281
      <title>Installing DRBD</title>
282

    
283
      <para>
284
        Recommended on all nodes: <ulink
285
        url="http://www.drbd.org/">DRBD</ulink> is required if you
286
        want to use the high availability (HA) features of Ganeti, but
287
        optional if you don't require HA or only run Ganeti on
288
        single-node clusters. You can upgrade a non-HA cluster to an
289
        HA one later, but you might need to export and re-import all
290
        your instances to take advantage of the new features.
291
      </para>
292

    
293
      <para>
294
        Supported DRBD version: the <literal>0.7</literal>
295
        series. It's recommended to have at least version
296
        <literal>0.7.24</literal> if you use <command>udev</command>
297
        since older versions have a bug related to device discovery
298
        which can be triggered in cases of hard drive failure.
299
      </para>
300

    
301
      <para>
302
        Now the bad news: unless your distribution already provides it
303
        installing DRBD might involve recompiling your kernel or
304
        anyway fiddling with it. Hopefully at least the Xen-ified
305
        kernel source to start from will be provided.
306
      </para>
307

    
308
      <para>
309
        The good news is that you don't need to configure DRBD at all.
310
        Ganeti will do it for you for every instance you set up.  If
311
        you have the DRBD utils installed and the module in your
312
        kernel you're fine. Please check that your system is
313
        configured to load the module at every boot, and that it
314
        passes the following option to the module:
315
        <computeroutput>minor_count=64</computeroutput> (this will
316
        allow you to use up to 32 instances per node).
317
      </para>
318

    
319
      <formalpara><title>Debian</title>
320
        <para>
321
         You can just install (build) the DRBD 0.7 module with the
322
         following commands (make sure you are running the Xen
323
         kernel):
324
        </para>
325
      </formalpara>
326

    
327
      <screen>
328
apt-get install drbd0.7-module-source drbd0.7-utils
329
m-a update
330
m-a a-i drbd0.7
331
echo drbd minor_count=64 >> /etc/modules
332
modprobe drbd minor_count=64
333
      </screen>
334

    
335
      <para>
336
        It is also recommended that you comment out the default
337
        resources in the <filename>/etc/dbrd.conf</filename> file, so
338
        that the init script doesn't try to configure any drbd
339
        devices. You can do this by prefixing all
340
        <literal>resource</literal> lines in the file with the keyword
341
        <literal>skip</literal>, like this:
342
      </para>
343

    
344
      <screen>
345
skip resource r0 {
346
...
347
}
348

    
349
skip resource "r1" {
350
...
351
}
352
      </screen>
353

    
354
    </sect2>
355

    
356
    <sect2>
357
      <title>Other required software</title>
358

    
359
      <para>Besides Xen and DRBD, you will need to install the
360
      following (on all nodes):</para>
361

    
362
      <itemizedlist>
363
        <listitem>
364
          <simpara><ulink url="http://sourceware.org/lvm2/">LVM
365
          version 2</ulink></simpara>
366
        </listitem>
367
        <listitem>
368
          <simpara><ulink
369
          url="http://www.openssl.org/">OpenSSL</ulink></simpara>
370
        </listitem>
371
        <listitem>
372
          <simpara><ulink
373
          url="http://www.openssh.com/portable.html">OpenSSH</ulink></simpara>
374
        </listitem>
375
        <listitem>
376
          <simpara><ulink url="http://bridge.sourceforge.net/">Bridge
377
          utilities</ulink></simpara>
378
        </listitem>
379
        <listitem>
380
          <simpara><ulink
381
          url="http://developer.osdl.org/dev/iproute2">iproute2</ulink></simpara>
382
        </listitem>
383
        <listitem>
384
          <simpara><ulink
385
          url="ftp://ftp.inr.ac.ru/ip-routing/iputils-current.tar.gz">arping</ulink>
386
          (part of iputils package)</simpara>
387
        </listitem>
388
        <listitem>
389
          <simpara><ulink
390
          url="http://www.kernel.org/pub/linux/utils/raid/mdadm/">mdadm</ulink>
391
          (Linux Software Raid tools)</simpara>
392
        </listitem>
393
        <listitem>
394
          <simpara><ulink url="http://www.python.org">Python 2.4</ulink></simpara>
395
        </listitem>
396
        <listitem>
397
          <simpara><ulink url="http://twistedmatrix.com/">Python
398
          Twisted library</ulink> - the core library is
399
          enough</simpara>
400
        </listitem>
401
        <listitem>
402
          <simpara><ulink
403
          url="http://pyopenssl.sourceforge.net/">Python OpenSSL
404
          bindings</ulink></simpara>
405
        </listitem>
406
        <listitem>
407
          <simpara><ulink
408
          url="http://www.undefined.org/python/#simplejson">simplejson Python
409
          module</ulink></simpara>
410
        </listitem>
411
        <listitem>
412
          <simpara><ulink
413
          url="http://pyparsing.wikispaces.com/">pyparsing Python
414
          module</ulink></simpara>
415
        </listitem>
416
      </itemizedlist>
417

    
418
      <para>
419
        These programs are supplied as part of most Linux
420
        distributions, so usually they can be installed via apt or
421
        similar methods. Also many of them will already be installed
422
        on a standard machine.
423
      </para>
424

    
425

    
426
      <formalpara><title>Debian</title>
427

    
428
      <para>You can use this command line to install all of them:</para>
429

    
430
      </formalpara>
431
      <screen>
432
# apt-get install lvm2 ssh bridge-utils iproute iputils-arping \
433
  python2.4 python-twisted-core python-pyopenssl openssl \
434
  mdadm
435
      </screen>
436

    
437
    </sect2>
438

    
439
  </sect1>
440

    
441

    
442
  <sect1>
443
    <title>Setting up the environment for Ganeti</title>
444

    
445
    <sect2>
446
      <title>Configuring the network</title>
447

    
448
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
449

    
450
      <para>
451
        Ganeti relies on Xen running in "bridge mode", which means the
452
        instances network interfaces will be attached to a software bridge
453
        running in dom0. Xen by default creates such a bridge at startup, but
454
        your distribution might have a different way to do things.
455
      </para>
456

    
457
      <para>
458
        Beware that the default name Ganeti uses is
459
        <hardware>xen-br0</hardware> (which was used in Xen 2.0)
460
        while Xen 3.0 uses <hardware>xenbr0</hardware> by
461
        default. The default bridge your Ganeti cluster will use for new
462
        instances can be specified at cluster initialization time.
463
      </para>
464

    
465
      <formalpara><title>Debian</title>
466
        <para>
467
          The recommended Debian way to configure the Xen bridge is to
468
          edit your <filename>/etc/network/interfaces</filename> file
469
          and substitute your normal Ethernet stanza with the
470
          following snippet:
471

    
472
        <screen>
473
auto xen-br0
474
iface xen-br0 inet static
475
        address <replaceable>YOUR_IP_ADDRESS</replaceable>
476
        netmask <replaceable>YOUR_NETMASK</replaceable>
477
        network <replaceable>YOUR_NETWORK</replaceable>
478
        broadcast <replaceable>YOUR_BROADCAST_ADDRESS</replaceable>
479
        gateway <replaceable>YOUR_GATEWAY</replaceable>
480
        bridge_ports eth0
481
        bridge_stp off
482
        bridge_fd 0
483
        </screen>
484
        </para>
485
      </formalpara>
486

    
487
     <para>
488
The following commands need to be executed on the local console
489
     </para>
490
      <screen>
491
ifdown eth0
492
ifup xen-br0
493
      </screen>
494

    
495
      <para>
496
        To check if the bridge is setup, use <command>ip</command>
497
        and <command>brctl show</command>:
498
      <para>
499

    
500
      <screen>
501
# ip a show xen-br0
502
9: xen-br0: &lt;BROADCAST,MULTICAST,UP,10000&gt; mtu 1500 qdisc noqueue
503
    link/ether 00:20:fc:1e:d5:5d brd ff:ff:ff:ff:ff:ff
504
    inet 10.1.1.200/24 brd 10.1.1.255 scope global xen-br0
505
    inet6 fe80::220:fcff:fe1e:d55d/64 scope link
506
       valid_lft forever preferred_lft forever
507

    
508
# brctl show xen-br0
509
bridge name     bridge id               STP enabled     interfaces
510
xen-br0         8000.0020fc1ed55d       no              eth0
511
      </screen>
512

    
513

    
514
    </sect2>
515

    
516
    <sect2>
517
      <title>Configuring LVM</title>
518

    
519

    
520
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
521

    
522
      <note>
523
        <simpara>The volume group is required to be at least
524
        <constant>20GiB</constant>.</simpara>
525
      </note>
526
      <para>
527
        If you haven't configured your LVM volume group at install
528
        time you need to do it before trying to initialize the Ganeti
529
        cluster. This is done by formatting the devices/partitions you
530
        want to use for it and then adding them to the relevant volume
531
        group:
532

    
533
       <screen>
534
pvcreate /dev/sda3
535
vgcreate xenvg /dev/sda3
536
       </screen>
537
or
538
       <screen>
539
pvcreate /dev/sdb1
540
pvcreate /dev/sdc1
541
vgcreate xenvg /dev/sdb1 /dev/sdc1
542
       </screen>
543
      </para>
544

    
545
      <para>
546
	If you want to add a device later you can do so with the
547
	<citerefentry><refentrytitle>vgextend</refentrytitle>
548
	<manvolnum>8</manvolnum></citerefentry> command:
549
      </para>
550

    
551
      <screen>
552
pvcreate /dev/sdd1
553
vgextend xenvg /dev/sdd1
554
      </screen>
555

    
556
      <formalpara>
557
        <title>Optional</title>
558
        <para>
559
          It is recommended to configure LVM not to scan the DRBD
560
          devices for physical volumes. This can be accomplished by
561
          editing <filename>/etc/lvm/lvm.conf</filename> and adding
562
          the <literal>/dev/drbd[0-9]+</literal> regular expression to
563
          the <literal>filter</literal> variable, like this:
564
<screen>
565
    filter = [ "r|/dev/cdrom|", "r|/dev/drbd[0-9]+|" ]
566
</screen>
567
        </para>
568
      </formalpara>
569

    
570
    </sect2>
571

    
572
    <sect2>
573
      <title>Installing Ganeti</title>
574

    
575
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
576

    
577
      <para>
578
        It's now time to install the Ganeti software itself.  Download
579
        the source from <ulink
580
        url="http://code.google.com/p/ganeti/"></ulink>.
581
      </para>
582

    
583
        <screen>
584
tar xvzf ganeti-1.2b1.tar.gz
585
cd ganeti-1.2b1
586
./configure --localstatedir=/var --sysconfdir=/etc
587
make
588
make install
589
mkdir /srv/ganeti/ /srv/ganeti/os /srv/ganeti/export
590
        </screen>
591

    
592
      <para>
593
        You also need to copy the file
594
        <filename>doc/examples/ganeti.initd</filename>
595
        from the source archive to
596
        <filename>/etc/init.d/ganeti</filename> and register it with
597
        your distribution's startup scripts, for example in Debian:
598
      </para>
599
      <screen>update-rc.d ganeti defaults 20 80</screen>
600

    
601
      <para>
602
        In order to automatically restart failed instances, you need
603
        to setup a cron job run the
604
        <computeroutput>ganeti-watcher</computeroutput> program. A
605
        sample cron file is provided in the source at
606
        <filename>doc/examples/ganeti.cron</filename> and you can
607
        copy that (eventually altering the path) to
608
        <filename>/etc/cron.d/ganeti</filename>
609
      </para>
610

    
611
    </sect2>
612

    
613
    <sect2>
614
      <title>Installing the Operating System support packages</title>
615

    
616
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
617

    
618
      <para>
619
        To be able to install instances you need to have an Operating
620
        System installation script. An example for Debian Etch is
621
        provided on the project web site.  Download it from <ulink
622
        url="http://code.google.com/p/ganeti/"></ulink> and follow the
623
        instructions in the <filename>README</filename> file.  Here is
624
        the installation procedure:
625
      </para>
626

    
627
      <screen>
628
cd /srv/ganeti/os
629
tar xvf instance-debian-etch-0.1.tar
630
mv instance-debian-etch-0.1 debian-etch
631
      </screen>
632

    
633
      <para>
634
        In order to use this OS definition, you need to have internet
635
        access from your nodes and have the <citerefentry>
636
        <refentrytitle>debootstrap</refentrytitle>
637
        <manvolnum>8</manvolnum></citerefentry>, <citerefentry>
638
        <refentrytitle>dump</refentrytitle><manvolnum>8</manvolnum>
639
        </citerefentry> and <citerefentry>
640
        <refentrytitle>restore</refentrytitle>
641
        <manvolnum>8</manvolnum> </citerefentry> commands installed on
642
        all nodes.
643
      </para>
644
      <formalpara>
645
        <title>Debian</title>
646
        <para>
647
          Use this command on all nodes to install the required
648
          packages:
649

    
650
          <screen>apt-get install debootstrap dump</screen>
651
        </para>
652
      </formalpara>
653

    
654
      <para>
655
        Alternatively, you can create your own OS definitions. See the
656
        manpage
657
        <citerefentry>
658
        <refentrytitle>ganeti-os-interface</refentrytitle>
659
        <manvolnum>8</manvolnum>
660
        </citerefentry>.
661
      </para>
662

    
663
    </sect2>
664

    
665
    <sect2>
666
      <title>Initializing the cluster</title>
667

    
668
      <para><emphasis role="strong">Mandatory:</emphasis> only on one
669
      node per cluster.</para>
670

    
671

    
672
      <para>The last step is to initialize the cluster. After you've repeated
673
        the above process on all of your nodes, choose one as the master, and execute:
674
      </para>
675

    
676
      <screen>
677
gnt-cluster init <replaceable>CLUSTERNAME</replaceable>
678
      </screen>
679

    
680
      <para>
681
        The <replaceable>CLUSTERNAME</replaceable> is a hostname,
682
        which must be resolvable (e.g. it must exist in DNS or in
683
        <filename>/etc/hosts</filename>) by all the nodes in the
684
        cluster. You must choose a name different from any of the
685
        nodes names for a multi-node cluster. In general the best
686
        choice is to have a unique name for a cluster, even if it
687
        consists of only one machine, as you will be able to expand it
688
        later without any problems.
689
      </para>
690

    
691
      <para>
692
        If the bridge name you are using is not
693
        <literal>xen-br0</literal>, use the <option>-b
694
        <replaceable>BRIDGENAME</replaceable></option> option to
695
        specify the bridge name. In this case, you should also use the
696
        <option>--master-netdev
697
        <replaceable>BRIDGENAME</replaceable></option> option with the
698
        same <replaceable>BRIDGENAME</replaceable> argument.
699
      </para>
700

    
701
      <para>
702
        You can use a different name than <literal>xenvg</literal> for
703
        the volume group (but note that the name must be identical on
704
        all nodes). In this case you need to specify it by passing the
705
        <option>-g <replaceable>VGNAME</replaceable></option> option
706
        to <computeroutput>gnt-cluster init</computeroutput>.
707
      </para>
708

    
709
      <para>
710
        You can also invoke the command with the
711
        <option>--help</option> option in order to see all the
712
        possibilities.
713
      </para>
714

    
715
    </sect2>
716

    
717
    <sect2>
718
      <title>Joining the nodes to the cluster</title>
719

    
720
      <para>
721
        <emphasis role="strong">Mandatory:</emphasis> for all the
722
        other nodes.
723
      </para>
724

    
725
      <para>
726
        After you have initialized your cluster you need to join the
727
        other nodes to it. You can do so by executing the following
728
        command on the master node:
729
      </para>
730
        <screen>
731
gnt-node add <replaceable>NODENAME</replaceable>
732
        </screen>
733
    </sect2>
734

    
735
    <sect2>
736
      <title>Separate replication network</title>
737

    
738
      <para><emphasis role="strong">Optional</emphasis></para>
739
      <para>
740
        Ganeti uses DRBD to mirror the disk of the virtual instances
741
        between nodes. To use a dedicated network interface for this
742
        (in order to improve performance or to enhance security) you
743
        need to configure an additional interface for each node.  Use
744
        the <option>-s</option> option with
745
        <computeroutput>gnt-cluster init</computeroutput> and
746
        <computeroutput>gnt-node add</computeroutput> to specify the
747
        IP address of this secondary interface to use for each
748
        node. Note that if you specified this option at cluster setup
749
        time, you must afterwards use it for every node add operation.
750
      </para>
751
    </sect2>
752

    
753
    <sect2>
754
      <title>Testing the setup</title>
755

    
756
      <para>
757

    
758
        Execute the <computeroutput>gnt-node list</computeroutput>
759
        command to see all nodes in the cluster:
760
      <screen>
761
# gnt-node list
762
Node              DTotal  DFree MTotal MNode MFree Pinst Sinst
763
node1.example.com 197404 197404   2047  1896   125     0     0
764
      </screen>
765
    </para>
766
  </sect2>
767

    
768
  <sect1>
769
    <title>Setting up and managing virtual instances</title>
770
    <sect2>
771
      <title>Setting up virtual instances</title>
772
      <para>
773
        This step shows how to setup a virtual instance with either
774
        non-mirrored disks (<computeroutput>plain</computeroutput>) or
775
        with network mirrored disks
776
        (<computeroutput>remote_raid1</computeroutput>).  All commands
777
        need to be executed on the Ganeti master node (the one on
778
        which <computeroutput>gnt-cluster init</computeroutput> was
779
        run).  Verify that the OS scripts are present on all cluster
780
        nodes with <computeroutput>gnt-os list</computeroutput>.
781
      </para>
782
      <para>
783
        To create a virtual instance, you need a hostname which is
784
        resolvable (DNS or <filename>/etc/hosts</filename> on all
785
        nodes). The following command will create a non-mirrored
786
        instance for you:
787
      </para>
788
      <screen>
789
gnt-instance add --node=node1 -o debian-etch -t plain inst1.example.com
790
* creating instance disks...
791
adding instance inst1.example.com to cluster config
792
Waiting for instance inst1.example.com to sync disks.
793
Instance inst1.example.com's disks are in sync.
794
creating os for instance inst1.example.com on node node1.example.com
795
* running the instance OS create scripts...
796
      </screen>
797

    
798
      <para>
799
        The above instance will have no network interface enabled.
800
        You can access it over the virtual console with
801
        <computeroutput>gnt-instance console
802
        <literal>inst1</literal></computeroutput>. There is no
803
        password for root.  As this is a Debian instance, you can
804
        modify the <filename>/etc/network/interfaces</filename> file
805
        to setup the network interface (<literal>eth0</literal> is the
806
        name of the interface provided to the instance).
807
      </para>
808

    
809
      <para>
810
        To create a network mirrored instance, change the argument to
811
        the <option>-t</option> option from <literal>plain</literal>
812
        to <literal>remote_raid1</literal> and specify the node on
813
        which the mirror should reside with the
814
        <option>--secondary-node</option> option, like this:
815
      </para>
816

    
817
      <screen>
818
# gnt-instance add -t remote_raid1 --secondary-node node1 \
819
  -n node2 -o debian-etch instance2
820
* creating instance disks...
821
adding instance instance2 to cluster config
822
Waiting for instance instance1 to sync disks.
823
- device sdb:  3.50% done, 304 estimated seconds remaining
824
- device sdb: 21.70% done, 270 estimated seconds remaining
825
- device sdb: 39.80% done, 247 estimated seconds remaining
826
- device sdb: 58.10% done, 121 estimated seconds remaining
827
- device sdb: 76.30% done, 72 estimated seconds remaining
828
- device sdb: 94.80% done, 18 estimated seconds remaining
829
Instance instance2's disks are in sync.
830
creating os for instance instance2 on node node2.example.com
831
* running the instance OS create scripts...
832
* starting instance...
833
      </screen>
834

    
835
    </sect2>
836

    
837
    <sect2>
838
      <title>Managing virtual instances</title>
839
      <para>
840
        All commands need to be executed on the Ganeti master node
841
      </para>
842

    
843
      <para>
844
        To access the console of an instance, use
845
        <computeroutput>gnt-instance console
846
        <replaceable>INSTANCENAME</replaceable></computeroutput>.
847
      </para>
848

    
849
      <para>
850
        To shutdown an instance, use <computeroutput>gnt-instance
851
        shutdown
852
        <replaceable>INSTANCENAME</replaceable></computeroutput>. To
853
        startup an instance, use <computeroutput>gnt-instance startup
854
        <replaceable>INSTANCENAME</replaceable></computeroutput>.
855
      </para>
856

    
857
      <para>
858
        To failover an instance to its secondary node (only possible
859
        in <literal>remote_raid1</literal> setup), use
860
        <computeroutput>gnt-instance failover
861
        <replaceable>INSTANCENAME</replaceable></computeroutput>.
862
      </para>
863

    
864
      <para>
865
        For more instance and cluster administration details, see the
866
        <emphasis>Ganeti administrator's guide</emphasis>.
867
      </para>
868

    
869
    </sect2>
870

    
871
  </sect1>
872

    
873
  </article>